REMANSO TALISMA, Brazil — The death of a myth begins with stinging eyes and heaving chests here on the edge of the Amazon rain forest.
Every year, fire envelops the jungle, throwing up inky billows of smoke that blot out the sun. Animals flee. Residents for miles around cry and wheeze, while the weak and unlucky develop serious respiratory problems.
When the burning season strikes, life and health in the Amazon falter, and color drains out of the riotous green landscape as great swaths of majestic trees, creeping vines, delicate bromeliads and hardy ferns are reduced to blackened stubble.
But more than just the land, these annual blazes also lay waste to a cherished notion that has roosted in the popular mind for decades: the idea of the rain forest as the "lungs of the world."
Ever since saving the Amazon became a fashionable cause in the 1980s, championed by Madonna, Sting and other celebrities, the jungle has consistently been likened to an enormous recycling plant that slurps up carbon dioxide and pumps out oxygen for us all to breathe, from Los Angeles to London to Lusaka.
Think again, scientists say.
Far from cleaning up the atmosphere, the Amazon is now a major source for pollution. Rampant burning and deforestation, mostly at the hands of illegal loggers and of ranchers, release hundreds of millions of tons of carbon dioxide into the skies each year.
Brazil now ranks as one of the world's leading producers of greenhouse gases, thanks in large part to the Amazon, the source for up to two-thirds of the country's emissions.
"It's not the lungs of the world," said Daniel Nepstad, an American ecologist who has studied the Amazon for 20 years. "It's probably burning up more oxygen now than it's producing."
Scientists such as Nepstad prefer to think of the world's largest tropical rain forest as Earth's air conditioner. The region's humidity, they say, is vital in climate regulation and cooling patterns in South America -- and perhaps as far away as Europe.
The Amazon's role as a source of pollution, not a remover of it, is directly linked to the galloping rate of destruction in the region over the last quarter-century.
The dense and steamy habitat straddles eight countries and is home to up to 20% of the world's fresh water and 30% of its plant and animal species.
Brazil's portion accounts for more than half the entire ecosystem. Official figures show that, on average, 7,500 square miles of rain forest were chopped and burned down in Brazil every year between 1979 and 2004. Over the 25 years, it's as if a forest the size of California had disappeared from the face of the Earth.
Such encroachment on virgin land is theoretically illegal or subject to tough regulation, but the government here lacks the resources -- some say the will -- to enforce environmental protection laws.
Loggers are typically the first to punch through, hacking crude roads and harvesting all the precious hardwoods they can find. One gang of woodcutters, in cahoots with crooked environmental-protection officials, cut down nearly $371 million worth of timber from 1990 until it was busted in the biggest sting operation of its kind in Brazil, authorities said last week.
Close on the loggers' heels are big ranchers and farmers, who torch the remaining vegetation to clear the way for cattle and crops such as soy, Brazil's new star export, which is claiming ever larger quantities of land.
Prime burning period in the Amazon runs from July to January, the dry season. In 2004, government satellite images of the forest registered 165,440 "hot spots," fires whose flames can shoot as high as 100 feet and push temperatures beyond 2,500 degrees.
These tremendous blazes spew about 200 million tons of carbon emissions into the atmosphere each year, which translates into several times that amount in actual carbon dioxide. In contrast, Brazil's consumption of fossil fuels, the chief source of greenhouse gases worldwide, creates less than half what the fires send up.
During burning season, dark palls of smoke settle over parts of the jungle for days.
"It becomes hard to see, and your eyes have problems. The kids all get sick and have trouble breathing," said Joaquim Borges da Silva, 42, a rural worker who lives in a small encampment here in Remanso Talisma, on the forest's outskirts.
Smoke grew so thick at one point last year that two cars on the road into the camp barreled into each other head-on, killing two people, Borges da Silva said. The fires also kill the game that workers and small settlers rely on for food.
He pointed out a charred tract of land, littered with stumps and felled trees that looked like so many toothpicks, where tractors working 24 hours a day for a month cleared 1,000 acres last year. Trucks rumbled in and out, loaded down with mahogany and cedar.
Farmers subsequently burned the area. Two months later, at the first rain, a small plane swooped in and dropped seeds.